WO2023025986A1 - Inorganic tfel display element and manufacturing method - Google Patents
Inorganic tfel display element and manufacturing method Download PDFInfo
- Publication number
- WO2023025986A1 WO2023025986A1 PCT/FI2022/050542 FI2022050542W WO2023025986A1 WO 2023025986 A1 WO2023025986 A1 WO 2023025986A1 FI 2022050542 W FI2022050542 W FI 2022050542W WO 2023025986 A1 WO2023025986 A1 WO 2023025986A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- layer
- display element
- layers
- sub
- electroluminescent display
- Prior art date
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 17
- 239000000463 material Substances 0.000 claims abstract description 28
- 239000010409 thin film Substances 0.000 claims abstract description 18
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 13
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims abstract description 13
- 229910000449 hafnium oxide Inorganic materials 0.000 claims abstract description 8
- WIHZLLGSGQNAGK-UHFFFAOYSA-N hafnium(4+);oxygen(2-) Chemical compound [O-2].[O-2].[Hf+4] WIHZLLGSGQNAGK-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000000758 substrate Substances 0.000 claims description 33
- 238000000034 method Methods 0.000 claims description 27
- 239000011521 glass Substances 0.000 claims description 26
- 238000000231 atomic layer deposition Methods 0.000 claims description 22
- 239000002243 precursor Substances 0.000 claims description 13
- 229910052984 zinc sulfide Inorganic materials 0.000 claims description 12
- 229910052735 hafnium Inorganic materials 0.000 claims description 7
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 claims description 7
- 125000002147 dimethylamino group Chemical group [H]C([H])([H])N(*)C([H])([H])[H] 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- 239000005083 Zinc sulfide Substances 0.000 claims description 4
- DRDVZXDWVBGGMH-UHFFFAOYSA-N zinc;sulfide Chemical compound [S-2].[Zn+2] DRDVZXDWVBGGMH-UHFFFAOYSA-N 0.000 claims description 4
- 239000007983 Tris buffer Substances 0.000 claims description 3
- CJNBYAVZURUTKZ-UHFFFAOYSA-N hafnium(IV) oxide Inorganic materials O=[Hf]=O CJNBYAVZURUTKZ-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052593 corundum Inorganic materials 0.000 abstract description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 157
- 238000000151 deposition Methods 0.000 description 12
- 239000011572 manganese Substances 0.000 description 11
- 238000012545 processing Methods 0.000 description 10
- 230000008021 deposition Effects 0.000 description 7
- HQWPLXHWEZZGKY-UHFFFAOYSA-N diethylzinc Chemical compound CC[Zn]CC HQWPLXHWEZZGKY-UHFFFAOYSA-N 0.000 description 5
- 229920003023 plastic Polymers 0.000 description 5
- 239000004020 conductor Substances 0.000 description 4
- 230000005684 electric field Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 238000005137 deposition process Methods 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 239000012697 Mn precursor Substances 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- 238000003877 atomic layer epitaxy Methods 0.000 description 2
- 238000010923 batch production Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 239000003989 dielectric material Substances 0.000 description 2
- 238000005401 electroluminescence Methods 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 238000010030 laminating Methods 0.000 description 2
- 238000000059 patterning Methods 0.000 description 2
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 102000014961 Protein Precursors Human genes 0.000 description 1
- 108010078762 Protein Precursors Proteins 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000005388 borosilicate glass Substances 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000009501 film coating Methods 0.000 description 1
- 230000002431 foraging effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000005283 ground state Effects 0.000 description 1
- JEGUKCSWCFPDGT-UHFFFAOYSA-N h2o hydrate Chemical compound O.O JEGUKCSWCFPDGT-UHFFFAOYSA-N 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 239000005340 laminated glass Substances 0.000 description 1
- 238000004020 luminiscence type Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229920000307 polymer substrate Polymers 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000005361 soda-lime glass Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000006557 surface reaction Methods 0.000 description 1
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 1
- LENZDBCJOHFCAS-UHFFFAOYSA-N tris Chemical compound OCC(N)(CO)CO LENZDBCJOHFCAS-UHFFFAOYSA-N 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/22—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
- C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
- C03C17/3411—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions with at least two coatings of inorganic materials
- C03C17/3429—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions with at least two coatings of inorganic materials at least one of the coatings being a non-oxide coating
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/57—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing manganese or rhenium
- C09K11/572—Chalcogenides
- C09K11/574—Chalcogenides with zinc or cadmium
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
- C09K11/7743—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing terbium
- C09K11/7744—Chalcogenides
- C09K11/7745—Chalcogenides with zinc or cadmium
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/305—Sulfides, selenides, or tellurides
- C23C16/306—AII BVI compounds, where A is Zn, Cd or Hg and B is S, Se or Te
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/40—Oxides
- C23C16/403—Oxides of aluminium, magnesium or beryllium
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
- C23C16/45523—Pulsed gas flow or change of composition over time
- C23C16/45525—Atomic layer deposition [ALD]
- C23C16/45527—Atomic layer deposition [ALD] characterized by the ALD cycle, e.g. different flows or temperatures during half-reactions, unusual pulsing sequence, use of precursor mixtures or auxiliary reactants or activations
- C23C16/45529—Atomic layer deposition [ALD] characterized by the ALD cycle, e.g. different flows or temperatures during half-reactions, unusual pulsing sequence, use of precursor mixtures or auxiliary reactants or activations specially adapted for making a layer stack of alternating different compositions or gradient compositions
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2218/00—Methods for coating glass
- C03C2218/10—Deposition methods
- C03C2218/15—Deposition methods from the vapour phase
- C03C2218/152—Deposition methods from the vapour phase by cvd
Definitions
- the present specification relates to electroluminescent displays , especially to inorganic thin film electroluminescent displays .
- Electroluminescent displays (below also "EL display” ) have specific properties , such as durability and capacity of functioning at low temperatures , which make them as an excellent display technology for the most challenging operating environments and conditions .
- an EL display Basically, the operation of an EL display is based on a luminescent material that emits light when exposed to an external electric field .
- the luminescent material is arranged as a thin luminescent layer generally having a thickness of less than 1000 nanometers , typically approximately 500 - 750 nanometers . For low voltage applications , the thickness may be also lower .
- the luminescent layer is provided between two conductive electrode layers that are electrically insulated from the luminescent layer with thin dielectric layers serving for electrical insulating . A voltage difference between the electrodes provides an electric field, by the ef fect of which the electrons move in the luminescent layer and some of them excite, in the luminescent layer, so-called luminescent centers which are formed by the doping material ( s ) of the luminescent layer . Light is emitted as the excitation of the luminescent centers is relaxed .
- An EL display element is conventionally manufactured by forming the core operating layers, namely, the dielectric layers, the luminescent layer, and the electrode layers, on a glass substrate having a thickness in the range of 1 mm. Some applications may require thinner substrates. For example, in applications where an EL display element is to be laminated within a glass panel for automotive windscreen, there is only a narrow gap which may have a thickness of some hundreds of micrometers available for the entire stack of the EL display, including the glass substrate thereof.
- Substrates with lower thickness may also be useful in applications where an EL display element is to be laminated on a curved, i.e. non-planar external substrate, or in applications of flexible display structure .
- plastic substrates instead of glass, plastic substrates may be desired to be used.
- Various film deposition processes may be used for manufacturing the layer stack of an EL display.
- One preferred technology is atomic layer deposition ALD enabling well controlled deposition of high-quality films .
- Plastic substrates as well as thinner glass substrates may limit the maximum processing temperature lower than the temperatures used in the conventional processes. From production efficiency point of view, suitability of the deposition processes for batch production may also be desirable .
- Batch production may require , for example , the precursors of the materials to be deposited to enable in the deposition atmosphere a vapor pressure which is not achievable by conventional sources .
- an inorganic, possibly AC ( alternating current ) drivable , thin film electroluminescent display element having a layer structure comprising a first dielectric layer, a luminescent layer, comprising a luminescent material , on the first dielectric layer, and a second dielectric layer on the luminescent layer .
- Each of the first and the second dielectric layers comprises nanolaminate with alternating aluminum oxide AI2O3 and hafnium oxide HfCy sub-layers , the nanolaminate having at least two sub-layers of both types .
- a method which may be used for manufacturing an electroluminescent display element of the first aspect .
- FIG . 1 illustrates a flow chart of a method for manufacturing an electroluminescent display element
- FIG . 2 illustrates an electroluminescent display element .
- FIG . 2 The drawing of FIG . 2 is not in scale .
- the method of FIG . 1 may be used for manufacturing an inorganic thin film electroluminescent display element .
- a “display element” refers to a structure for a display .
- a display element may be a complete , operable , standalone display device .
- the "element” may refer to a modular or inseparably integrated element as a part of a complete display device or display unit .
- Inorganic refers to inorganic type of materials of the display element .
- Thin film refers to the total thickness of the operational thin film layers of the EL display element , i . e . the layer stack without the transparent substrate thereof , being less than some tens of micrometres .
- the total thickness may be , for example , in the range of 1 to 10 pm . Typically, it is less than or equal to 3 pm .
- a complete inorganic thin film electroluminescence/electroluminescent (“EL" ) display element manufactured utilizing the method of FIG . 1 may comprise a dielectric layer - luminescent layer dielectric layer sub-structure positioned between first and second conductive electrode layers .
- the entire layer stack may be formed and lie on a transparent substrate formed of glass or plastic or some other suitable material .
- suitable electric field provided in the luminescent layer by supplying a voltage difference between the conductive electrode layers , electrons are discharged into the luminescent layer, giving rise to light emission as luminescence centers excited by the electrons return to their ground state .
- the method of FIG . 1 comprises , in operation 11 , forming a first dielectric layer which comprises nanolaminate material with alternating aluminum oxide I2O3 and hafnium oxide HfCy sub-layers , the nanolaminate having at least two sublayers of both materials .
- the nanolaminate has at least two sub-layers of aluminum oxide , and two sub-layers of hafnium oxide .
- Such alternating layers may be considered forming pairs of the two sub-layers of different materials .
- the nanolaminate may comprise any appropriate number of such pairs of two adj acent sub-layers of different materials , for example , 5 to 25 pairs .
- the nanolaminate may comprise at least ten pairs of sublayers , each HfCy sub-layer having a thickness of 0 . 5 to 3 nm .
- nanolaminate refers to the thickness of the alternating sub-layers lying in nanometer scale .
- the nanolaminate may have a total thickness of less than 300 nm .
- the total thickness of the nanolaminate may lie in the range some dozens of nanometers . It may be advantageous to have the total thickness of the nanolaminate higher than or equal to 50 nm .
- One or more , possibly most or al l HfO2 sub-layers may have a thickness in the range of 1 to 10 nanometers , preferably in the range of 1 to 3 nm, for example , about 2 nm .
- Amorphous nanolaminate is found to be better than crystalline from the leakage current and light transmi ssion points of view .
- already mere division of the dielectric material as such may improve the leakage current performance and thereby the reliability of the dielectric material .
- the nanolaminate of at least one of the dielectric layers may comprise at least ten HfCy sub-layers , each having a thickness in the range of 0 . 5 to 3 nm. This may be enable keeping individual HfCy sub-layers sufficiently low to avoid crystalli zation thereof , but however having the overall thickness of the dielectric layer sufficiently high .
- One or more , possibly most or al l AI2O3 sub-layers may have a thickness in the range of 1 to 10 nm, preferably in the range of 1 to 3 , for example , about 6 nm .
- the sub-layer thicknes s above may contribute to form a dielectric layer with good electrical properties .
- a dielectric layer may also have one or more additional aluminum oxide and/or hafnium oxide sublayers . Then, the entire dielectric layer may have an even or odd total number of sub-layers . Such additional layer ( s ) may have thickness (es ) different from the sublayers of the actual nanolaminate part of the dielectric layer .
- a dielectric layer may have a sub-layer of aluminum oxide as the sub-layer adj acent to the luminescent layer .
- Such sub-layer may be part of the nanolaminate or an additional sub-layer . In the latter case , it may have thickness higher than the aluminum oxide sub-layers of the nanolaminate . This may result in higher brightness of the EL display element .
- the first dielectric layer is formed in operation 11 by atomic layer deposition ALD .
- a maximum proces sing temperature of 150 to 350 °C for example , about 250 °C, may be used .
- Atomic layer deposition ALD refers to a thin film technology enabling accurate and well-controlled production of thin film coatings with nanometer-scaled thicknesses .
- ALD may also be called Atomic Layer Epitaxy ALE .
- the deposition surface is alternately exposed to at least two precursors , one precursor at a time , to form on the depos ition surface a coating by alternately repeating essentially selflimiting surface reactions between the deposition surface and the precursors .
- the deposited material is "grown" molecule layer by molecule layer .
- the accuracy of ALD in the dielectric layer formation may result in high electrical performance of the device .
- Maximum processing temperature of the ALD process refers to both the maximum temperature in the ALD reactor chamber as well as the maximum temperatures of the precursors and any carrier gases supplied therein . Thus , neither the temperature of the reactor chamber nor the temperature of any gas suppl ied therein may exceed the maximum temperature .
- tris (dimethylamino ) cyclopentadienylhaf nium CpHf (NMe2 ) 3 is used as the precursor for hafnium in the ALD process .
- HyALDTM Tris (dimethylamino ) cyclopentadienylhaf nium CpHf (NMe2 ) 3 is commercially provided by Air Liquide with a trade name HyALDTM .
- HyALDTM is a liquid-form precursor enabl ing achieving sufficiently high vapor pressure of the deposition atmosphere for efficient batch processing of a large amount of EL display elements at the same time .
- precursors in the ALD process may be , for example , trimethylaluminum TMA for aluminum and water H2O or ozone O3 for oxygen .
- any other appropriate deposition method and precursors may be used .
- the maximum processing temperature is also then limited to the range specified above .
- a luminescent layer comprising a luminescent material is formed on the first dielectric layer .
- the luminescent layer comprising a luminescent material may refer to the luminescent layer entirely consisting of the luminescent material . Alternatively, there may be one or more other materials also present in the luminescent layer .
- the luminescent layer is deposited by atomic layer deposition ALD with a maximum process temperature in the range of 125 to 300 ° C, preferably 175 to 250 ° C or 200 to 225 ° C, for example .
- the luminescent material may be, for example, manganese doped zinc sulfide ZnS:Mn or terbium-doped zinc sulfide ZnS:Tb.
- Known precursors may be used to deposit the luminescent material.
- ZnS:Mn, diethylzinc DEZ, hydrogen sulfide H2S, and Mn(thd)s may be used as precursors.
- Mn precursors are Mn(CsH 5 )2 and its alkyl-, aryl- or carbonyl- substituted derivatives .
- the "luminescent layer” serves as a core part of the completed electroluminescent display element, emitting light when exposed to suitable electric field.
- This layer and/or the light emitting material thereof may also be called “phosphor”.
- a layer or a layer structure lying "on” another layer or substrate does not necessarily lie “directly” on that another layer or substrate.
- a layer structure of a dielectric layer, a luminescent layer, and a dielectric layer lying on a transparent substrate does not exclude the possibility of a conductive electrode layer lying between the substrate and said layer structure.
- high quality and stable luminescent layer of an EL display element may be produced in as low temperatures as 300 °C and lower .
- the dielectric layers may be formed using maximum processing temperatures such as 150 to 350 °C, for example , about 250 °C, using such low maximum processing temperatures for the luminescent layer may provide great advantages . Namely, then the entire process of forming the dielectric layers and the luminescent layer may take place in temperatures , for example , not substantially exceeding 300 °C .
- the latter is of particular importance when taking into account that in typical manufacturing processes , the glass sheets are conveyed automatically and, to save floor space of the manufacture , the glasses are held and transferred vertically or almost vertically, e . g . at 80 degrees angle relative to hori zon . Then, if the glass sheets become so thin that they start bending under their own weight , the conveying process becomes considerably more difficult .
- a typical laminated wind screen assembly comprises a glass plate with a thickness of 2.5 mm, an interlayer of a binder, such as Polyvinyl butyral (PVB) , and another glass plate of 2.5 mm.
- PVB Polyvinyl butyral
- Typical standard thicknesses for the binder layer are 0.38 mm, 0.76 mm, and 1.14 mm. Such assemblies may be referred to, according to the overall thickness thereof, for example, as "5.38 laminated glass". With this kind of glass assembly, the transparent EL display shall have a thickness of less than 0.38/0.76/1.14 mm, taking into account that usually a binder layer of 10 pm or somewhat less is needed at least on one side of the EL display to attach the display to the assembly.
- the EL display element may be formed so as to be flexible allowing, for example, laminating thereof on curved and/or flexible external substrates.
- the low maximum processing temperatures may enable forming the EL display element layers even on plastic substrates.
- a second dielectric layer comprising nanolaminate material with alternating aluminum oxide AI2O3 and hafnium oxide HfCy sub-layers is formed on the on the luminescent layer.
- the second dielectric layer may be formed similarly to the first dielectric layer discussed above.
- FIG . 1 manufacturing of only the dielectric layers and the luminescent layer is illustrated .
- Complete manufacturing process may further comprise , for example , forming a first conductive electrode layer on the transparent substrate , and forming a second conductive electrode layer on the second dielectric layer .
- additional layers for example, for protective and/or passivating purposes may be formed . In such operations , principles and processes as such known in the art may be used .
- the EL display element manufactured in the method of FIG 1 may be a segment type display element or a matrix type display element .
- the first and the second conductive electrode layers may be patterned in accordance with the type of the display element .
- the first and the second conductive electrode layers may be patterned to form rows and columns , whereby pixels are formed at the sites where the rows and the columns of the different electrode layers intersect . As a voltage is applied between such intersecting electrodes , electroluminescence appears in the phosphor layer at the relevant pixel .
- the active areas i . e . the light emitting areas of the display can be formed by patterning the first and the second conductive electrode layers in accordance with the desired light emitting segment arrangement . Thereby, for example , 7 - segment number displays or designs displaying discrete icons or symbols at predetermined locations may be implemented .
- the EL display element 20 of FIG . 2 may be manufactured generally in accordance with any of the embodiments of the method discussed above with reference to FIG . 1 .
- What is stated above about the EL display manufactured by the method discussed with reference to FIG. 1 applies, mutatis mutandis , also to the EL display element 20 of FIG. 2.
- What is stated below about the manufacturing method of the EL display discussed with reference to FIG. 2 applies, mutatis mutandis , also to the manufacturing method of FIG. 2.
- the EL display element 20 comprises, and the layers thereof are formed on a glass substrate 21 which may have a thickness, for example, in the range of 100 to 500 pm, for example, about 400 pm. It is possible to use even as low glass substrate thicknesses as less than or equal to 100 pm. In other embodiments, thicker glass substrates may be used.
- the glass substrate may be formed of, for example, soda lime glass, borosilicate glass, or any other glass material with sufficient transparency.
- substrates formed of other materials may be used, such as plastic or polymer substrates which may provide greater mechanical durability or flexibility than glass.
- a first or lower conductive electrode layer 22 is formed as an array of conductor stripes on the glass substrate.
- the conductive electrode layer may be first deposited, for example, by ALD, and then patterned accordance with the desired patterning by means of any appropriate lithographic operations.
- the HfO2 and AI2O3 sublayers may have thicknesses as discussed above with reference to FIG. 1.
- the AI2O3 sub-layers of the nanolaminate may have a thickness in the range of 1 to 10 nm or 3 to 9 nm, for example, about 6 nm.
- the total thickness of the first dielectric layer may be, for example, in a range of 50 to 250 nm.
- a luminescent layer 26 lies on the first dielectric layer. It may be formed, for example, of ZnS:Mn, deposited by ALD with maximum process temperature as discussed above with reference to FIG. 1, using DEZ, H2S, and Mn(thd)s as precursors. Other possible Mn precursors are Mn(CsH 5 )2 and its alkyl-, aryl- or carbonyl- substituted derivatives.
- the luminescent layer may have a thickness, for example, in a range of 400 to 1000 nm.
- second dielectric layer 27 which may be substantially similar to the first dielectric layer, comprising nanolaminate with alternating AI2O3 and HfO2 sub-layers 28, 29.
- the first dielectric layer 23 has as its uppermost sublayer, adjacent to the luminescent layer 26, an additional sub-layer 24' of aluminum oxide AI2O3.
- the second dielectric layer 27 has as its lowermost sub-layer, adjacent to the luminescent layer 26, an additional sub-layer 28' of aluminum oxide AI2O3.
- Those aluminum oxide sub-layers have thicknesses higher than the aluminum oxide sub-layers of the actual nanolaminates.
- the thicknesses of the additional sublayers may lie, for example, in the range of 5 to 25 nm.
- second conductive electrode layer 30 which may be substantially similar to the first conductive electrode layer 22, with the stripes 31 thereof however being directed perpendicularly to , or otherwise at an angle relative to , the conductor stripes of the first dielectric layer 22 .
- the EL display element may be transparent .
- the first and the second electrode layers may be formed of a transparent conductor material such as , for example , indium tin oxide ITO .
- suitable materials include , for example , aluminum doped zinc oxide AZO .
- the display element 20 of FIG . 2 thus has a matrix electrode configuration .
- segmented electrode configurations may be used .
- light-emitting areas in the form of pixels 32 are formed in the luminescent layer 26 at positions where the conductor stripes of the first and the second conductive electrode layers intersect .
- any appropriate further layers and/or elements may be present in an EL display element in addition to those illustrated in FIG . 2 .
- hafnium content of the first and/or the second dielectric layer is preferably at least 10 % by mass . This refers to the mass of the hafnium contained in a dielectric layer being at least 10 % of the overall mass of that layer .
- first and/or second dielectric layer where the hafnium content is at least 10 % by mass aluminum content is preferably at least 5% by mas s . This refers to the mass of the aluminum contained in such dielectric layer being at least 5% of the overall mass of that layer .
- the EL display element of FIG . 2 may provide various great advantages .
- the thin glass substrate serves for achieving a low overall thickness of the EL display component .
- This enables having the overall EL display element as a flexible structure which may be further laminated or otherwise attached to a flexible and/or curved external substrate .
- the EL display element in accordance with that of FIG . 2 has been found to have excellent stability performance .
- Enhanced stability results in reduced need for aging the displays in the manufacturing phase .
- the stability of the voltage-luminance dependency may be greatly advantageous from the display element driving scheme points of view .
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Electroluminescent Light Sources (AREA)
Abstract
An inorganic thin film electroluminescent display element (20) having a layer structure comprising: a first dielectric layer (23), a luminescent layer (26), comprising a luminescent material, on the first dielectric layer, and a second dielectric layer (27) on the luminescent layer. Each of the first and the second dielectric layers (23, 27) comprises nanolaminate with alternating aluminum oxide Al2O3 and hafnium oxide HfO2 sub-layers (24, 25, 28, 29), the nanolaminate having at least two sub-layers of both types and a thickness of less than or equal to 300 nm.
Description
INORGANIC TFEL DISPLAY ELEMENT AND MANUFACTURING METHOD
TECHNICAL FIELD
The present specification relates to electroluminescent displays , especially to inorganic thin film electroluminescent displays .
BACKGROUND
Electroluminescent displays (below also "EL display" ) have specific properties , such as durability and capacity of functioning at low temperatures , which make them as an excellent display technology for the most challenging operating environments and conditions .
Basically, the operation of an EL display is based on a luminescent material that emits light when exposed to an external electric field .
In inorganic EL displays provided as thin film structures , the luminescent material is arranged as a thin luminescent layer generally having a thickness of less than 1000 nanometers , typically approximately 500 - 750 nanometers . For low voltage applications , the thickness may be also lower . The luminescent layer is provided between two conductive electrode layers that are electrically insulated from the luminescent layer with thin dielectric layers serving for electrical insulating . A voltage difference between the electrodes provides an electric field, by the ef fect of which the electrons move in the luminescent layer and some of them excite, in the luminescent layer, so-called luminescent centers which are formed by the doping material ( s ) of the luminescent layer . Light is emitted as the excitation of the luminescent centers is relaxed .
The basic technology of EL displays is generally known and has been described extensively e . g . in
"Electroluminescent Displays" (Yoshimasa A. Ono, World Scientific Publishing Co., 1995 (ISBN 981-02-1920-0) in Chapters 3,5 and 8.
An EL display element is conventionally manufactured by forming the core operating layers, namely, the dielectric layers, the luminescent layer, and the electrode layers, on a glass substrate having a thickness in the range of 1 mm. Some applications may require thinner substrates. For example, in applications where an EL display element is to be laminated within a glass panel for automotive windscreen, there is only a narrow gap which may have a thickness of some hundreds of micrometers available for the entire stack of the EL display, including the glass substrate thereof.
Substrates with lower thickness may also be useful in applications where an EL display element is to be laminated on a curved, i.e. non-planar external substrate, or in applications of flexible display structure .
In some applications, instead of glass, plastic substrates may be desired to be used.
Various film deposition processes may be used for manufacturing the layer stack of an EL display. One preferred technology is atomic layer deposition ALD enabling well controlled deposition of high-quality films .
One factor affecting the feasibility of ALD and other deposition processes is the processing temperature. Plastic substrates as well as thinner glass substrates may limit the maximum processing temperature lower than the temperatures used in the conventional processes.
From production efficiency point of view, suitability of the deposition processes for batch production may also be desirable . Batch production may require , for example , the precursors of the materials to be deposited to enable in the deposition atmosphere a vapor pressure which is not achievable by conventional sources .
Improved solutions are thereby needed .
SUMMARY
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description . This Summary is not intended to identify key features or essential features of the claimed subj ect matter, nor is it intended to be used to limit the scope of the claimed subj ect matter .
In one aspect , an inorganic, possibly AC ( alternating current ) drivable , thin film electroluminescent display element is disclosed, the display element having a layer structure comprising a first dielectric layer, a luminescent layer, comprising a luminescent material , on the first dielectric layer, and a second dielectric layer on the luminescent layer .
Each of the first and the second dielectric layers comprises nanolaminate with alternating aluminum oxide AI2O3 and hafnium oxide HfCy sub-layers , the nanolaminate having at least two sub-layers of both types .
In a second aspect , a method is disclosed which may be used for manufacturing an electroluminescent display element of the first aspect .
BRIEF DESCRIPTION OF THE DRAWINGS
The present description will be better understood from the following detailed description read in light of the accompanying drawings , wherein :
FIG . 1 illustrates a flow chart of a method for manufacturing an electroluminescent display element ; and
FIG . 2 illustrates an electroluminescent display element .
The drawing of FIG . 2 is not in scale .
DETAILED DESCRIPTION
The method of FIG . 1 may be used for manufacturing an inorganic thin film electroluminescent display element .
A "display element" refers to a structure for a display . A display element may be a complete , operable , standalone display device . Alternatively, the "element" may refer to a modular or inseparably integrated element as a part of a complete display device or display unit .
" Inorganic" refers to inorganic type of materials of the display element .
"Thin film" refers to the total thickness of the operational thin film layers of the EL display element , i . e . the layer stack without the transparent substrate thereof , being less than some tens of micrometres . The total thickness may be , for example , in the range of 1 to 10 pm . Typically, it is less than or equal to 3 pm .
Generally, a complete inorganic thin film electroluminescence/electroluminescent ("EL" ) display element manufactured utilizing the method of FIG . 1 may comprise a dielectric layer - luminescent layer
dielectric layer sub-structure positioned between first and second conductive electrode layers . The entire layer stack may be formed and lie on a transparent substrate formed of glass or plastic or some other suitable material . In operation, with suitable electric field provided in the luminescent layer by supplying a voltage difference between the conductive electrode layers , electrons are discharged into the luminescent layer, giving rise to light emission as luminescence centers excited by the electrons return to their ground state .
The method of FIG . 1 comprises , in operation 11 , forming a first dielectric layer which comprises nanolaminate material with alternating aluminum oxide I2O3 and hafnium oxide HfCy sub-layers , the nanolaminate having at least two sublayers of both materials . Thus , the nanolaminate has at least two sub-layers of aluminum oxide , and two sub-layers of hafnium oxide .
Such alternating layers may be considered forming pairs of the two sub-layers of different materials . The nanolaminate may comprise any appropriate number of such pairs of two adj acent sub-layers of different materials , for example , 5 to 25 pairs . In an embodiment , the nanolaminate may comprise at least ten pairs of sublayers , each HfCy sub-layer having a thickness of 0 . 5 to 3 nm .
The pref ix "nano" in the term "nanolaminate" refers to the thickness of the alternating sub-layers lying in nanometer scale . The nanolaminate may have a total thickness of less than 300 nm . For example , the total thickness of the nanolaminate may lie in the range some dozens of nanometers . It may be advantageous to have the total thickness of the nanolaminate higher than or equal to 50 nm .
One or more , possibly most or al l HfO2 sub-layers may have a thickness in the range of 1 to 10 nanometers , preferably in the range of 1 to 3 nm, for example , about 2 nm . By not forming the sub-layers too thick may enable preventing HfO2 crystalli zation, as HfO2 tends to crystalli ze as the layer thickness increases . Amorphous nanolaminate is found to be better than crystalline from the leakage current and light transmi ssion points of view . In addition, already mere division of the dielectric material as such may improve the leakage current performance and thereby the reliability of the dielectric material .
The nanolaminate of at least one of the dielectric layers may comprise at least ten HfCy sub-layers , each having a thickness in the range of 0 . 5 to 3 nm. This may be enable keeping individual HfCy sub-layers sufficiently low to avoid crystalli zation thereof , but however having the overall thickness of the dielectric layer sufficiently high .
One or more , possibly most or al l AI2O3 sub-layers may have a thickness in the range of 1 to 10 nm, preferably in the range of 1 to 3 , for example , about 6 nm .
The sub-layer thicknes s above may contribute to form a dielectric layer with good electrical properties .
In addition to the paired sub-layers of the nanolaminate , a dielectric layer may also have one or more additional aluminum oxide and/or hafnium oxide sublayers . Then, the entire dielectric layer may have an even or odd total number of sub-layers . Such additional layer ( s ) may have thickness (es ) different from the sublayers of the actual nanolaminate part of the dielectric layer .
A dielectric layer may have a sub-layer of aluminum oxide as the sub-layer adj acent to the luminescent layer . Such sub-layer may be part of the nanolaminate or an additional sub-layer . In the latter case , it may have thickness higher than the aluminum oxide sub-layers of the nanolaminate . This may result in higher brightness of the EL display element .
In the example of FIG . 1 , the first dielectric layer is formed in operation 11 by atomic layer deposition ALD . A maximum proces sing temperature of 150 to 350 °C , for example , about 250 °C, may be used .
"Atomic layer deposition ALD" refers to a thin film technology enabling accurate and well-controlled production of thin film coatings with nanometer-scaled thicknesses . ALD may also be called Atomic Layer Epitaxy ALE . In an ALD process , the deposition surface is alternately exposed to at least two precursors , one precursor at a time , to form on the depos ition surface a coating by alternately repeating essentially selflimiting surface reactions between the deposition surface and the precursors . As a result , the deposited material is "grown" molecule layer by molecule layer .
The accuracy of ALD in the dielectric layer formation may result in high electrical performance of the device .
"Maximum processing temperature" of the ALD process refers to both the maximum temperature in the ALD reactor chamber as well as the maximum temperatures of the precursors and any carrier gases supplied therein . Thus , neither the temperature of the reactor chamber nor the temperature of any gas suppl ied therein may exceed the maximum temperature .
Preferably, tris (dimethylamino ) cyclopentadienylhaf nium CpHf (NMe2 ) 3 is used as the precursor for hafnium in the ALD process .
Tris (dimethylamino ) cyclopentadienylhaf nium CpHf (NMe2 ) 3 is commercially provided by Air Liquide with a trade name HyALD™ . HyALD™ is a liquid-form precursor enabl ing achieving sufficiently high vapor pressure of the deposition atmosphere for efficient batch processing of a large amount of EL display elements at the same time .
Other precursors in the ALD process may be , for example , trimethylaluminum TMA for aluminum and water H2O or ozone O3 for oxygen .
In other embodiments , any other appropriate deposition method and precursors may be used . Preferably, the maximum processing temperature is also then limited to the range specified above .
Next , in operation 12 , a luminescent layer comprising a luminescent material is formed on the first dielectric layer .
The luminescent layer comprising a luminescent material may refer to the luminescent layer entirely consisting of the luminescent material . Alternatively, there may be one or more other materials also present in the luminescent layer .
It the example of Fig . 1 , the luminescent layer is deposited by atomic layer deposition ALD with a maximum process temperature in the range of 125 to 300 ° C, preferably 175 to 250 ° C or 200 to 225 ° C, for example ,
The luminescent material may be, for example, manganese doped zinc sulfide ZnS:Mn or terbium-doped zinc sulfide ZnS:Tb.
Known precursors may be used to deposit the luminescent material. For example, in the case of ZnS:Mn, diethylzinc DEZ, hydrogen sulfide H2S, and Mn(thd)s may be used as precursors. Other possible Mn precursors are Mn(CsH5)2 and its alkyl-, aryl- or carbonyl- substituted derivatives .
As discussed above, the "luminescent layer" serves as a core part of the completed electroluminescent display element, emitting light when exposed to suitable electric field. This layer and/or the light emitting material thereof may also be called "phosphor".
Depositing a layer "on" a substrate or on a previously deposited layer does not necessitate the deposition taking place "directly" on the substrate or on the previously deposited layer, but one or more intermediate layers may be formed therebetween. Correspondingly, a layer or a layer structure lying "on" another layer or substrate does not necessarily lie "directly" on that another layer or substrate. For example, a layer structure of a dielectric layer, a luminescent layer, and a dielectric layer lying on a transparent substrate does not exclude the possibility of a conductive electrode layer lying between the substrate and said layer structure.
In conventional ALD processes for depositing luminescent materials such as ZnS:Mn, relatively high temperatures are used. For example, maximum processing temperatures in the range of 500 - 530 °C are typically used. Some examples of depositing a ZnS:Mn luminescent layer in an EL display with ATO dielectric layers using diethylzinc
DEZ , hydrogen sulfide H2 S , and Mn ( thd) 3 as precursors is discussed in US 6113977 A . In those examples , process temperatures of 350 and 450 °C were used .
The inventors have now surprisingly found, in contrast to the establ ished understanding in the art , that with Al2O3/HfO2 nanolaminate in the dielectric layers , high quality and stable luminescent layer of an EL display element may be produced in as low temperatures as 300 °C and lower . As the dielectric layers may be formed using maximum processing temperatures such as 150 to 350 °C, for example , about 250 °C, using such low maximum processing temperatures for the luminescent layer may provide great advantages . Namely, then the entire process of forming the dielectric layers and the luminescent layer may take place in temperatures , for example , not substantially exceeding 300 °C .
This may enable forming the EL display element layers on very thin glass substrates having thicknesses , for example , in the range of 100 - 400 pm or even lower without the risk that the glass substrate would lose its rigidity in result of softening . The latter is of particular importance when taking into account that in typical manufacturing processes , the glass sheets are conveyed automatically and, to save floor space of the manufacture , the glasses are held and transferred vertically or almost vertically, e . g . at 80 degrees angle relative to hori zon . Then, if the glass sheets become so thin that they start bending under their own weight , the conveying process becomes considerably more difficult . Further, in higher temperatures , the very thin sheets may deform from a uniform and flat shape to an unwanted wrinkled or crumpled shape if they are not completely evenly supported, even when held hori zontally, let alone in vertical or semi-vertical position .
Such thin substrates facilitate producing the entire EL display element so as to have a total thickness clearly below that of the conventional EL displays. This may enable, for example, manufacturing of EL display elements with a total thickness allowing laminating the EL display within a glass panel for automotive wind screen. A typical laminated wind screen assembly comprises a glass plate with a thickness of 2.5 mm, an interlayer of a binder, such as Polyvinyl butyral (PVB) , and another glass plate of 2.5 mm. Typical standard thicknesses for the binder layer are 0.38 mm, 0.76 mm, and 1.14 mm. Such assemblies may be referred to, according to the overall thickness thereof, for example, as "5.38 laminated glass". With this kind of glass assembly, the transparent EL display shall have a thickness of less than 0.38/0.76/1.14 mm, taking into account that usually a binder layer of 10 pm or somewhat less is needed at least on one side of the EL display to attach the display to the assembly.
Further, with such low glass substrates, the EL display element may be formed so as to be flexible allowing, for example, laminating thereof on curved and/or flexible external substrates.
In addition, the low maximum processing temperatures may enable forming the EL display element layers even on plastic substrates.
In operation 13, a second dielectric layer comprising nanolaminate material with alternating aluminum oxide AI2O3 and hafnium oxide HfCy sub-layers is formed on the on the luminescent layer. The second dielectric layer may be formed similarly to the first dielectric layer discussed above.
In FIG . 1 , manufacturing of only the dielectric layers and the luminescent layer is illustrated . Complete manufacturing process may further comprise , for example , forming a first conductive electrode layer on the transparent substrate , and forming a second conductive electrode layer on the second dielectric layer . In addition to any appropriate additional layers , for example, for protective and/or passivating purposes may be formed . In such operations , principles and processes as such known in the art may be used .
The EL display element manufactured in the method of FIG 1 may be a segment type display element or a matrix type display element . The first and the second conductive electrode layers may be patterned in accordance with the type of the display element .
For example , in the case of a matrix-type display element , the first and the second conductive electrode layers may be patterned to form rows and columns , whereby pixels are formed at the sites where the rows and the columns of the different electrode layers intersect . As a voltage is applied between such intersecting electrodes , electroluminescence appears in the phosphor layer at the relevant pixel . In the case of a segment-type display element , the active areas , i . e . the light emitting areas of the display can be formed by patterning the first and the second conductive electrode layers in accordance with the desired light emitting segment arrangement . Thereby, for example , 7 - segment number displays or designs displaying discrete icons or symbols at predetermined locations may be implemented .
The EL display element 20 of FIG . 2 may be manufactured generally in accordance with any of the embodiments of the method discussed above with reference to FIG . 1 .
What is stated above about the EL display manufactured by the method discussed with reference to FIG. 1 applies, mutatis mutandis , also to the EL display element 20 of FIG. 2. The same applies vice versa: What is stated below about the manufacturing method of the EL display discussed with reference to FIG. 2 applies, mutatis mutandis , also to the manufacturing method of FIG. 2.
The EL display element 20 comprises, and the layers thereof are formed on a glass substrate 21 which may have a thickness, for example, in the range of 100 to 500 pm, for example, about 400 pm. It is possible to use even as low glass substrate thicknesses as less than or equal to 100 pm. In other embodiments, thicker glass substrates may be used.
The glass substrate may be formed of, for example, soda lime glass, borosilicate glass, or any other glass material with sufficient transparency. In some embodiments, substrates formed of other materials may be used, such as plastic or polymer substrates which may provide greater mechanical durability or flexibility than glass.
A first or lower conductive electrode layer 22 is formed as an array of conductor stripes on the glass substrate. The conductive electrode layer may be first deposited, for example, by ALD, and then patterned accordance with the desired patterning by means of any appropriate lithographic operations.
A first or lower dielectric layer 23, comprising nanolaminate with alternating AI2O3 and HfO2 sub-layers 24, 25, lies on the glass substrate 21 and the first conductive electrode layer 22. The HfO2 and AI2O3 sublayers may have thicknesses as discussed above with
reference to FIG. 1. The AI2O3 sub-layers of the nanolaminate may have a thickness in the range of 1 to 10 nm or 3 to 9 nm, for example, about 6 nm. The total thickness of the first dielectric layer may be, for example, in a range of 50 to 250 nm.
A luminescent layer 26 lies on the first dielectric layer. It may be formed, for example, of ZnS:Mn, deposited by ALD with maximum process temperature as discussed above with reference to FIG. 1, using DEZ, H2S, and Mn(thd)s as precursors. Other possible Mn precursors are Mn(CsH5)2 and its alkyl-, aryl- or carbonyl- substituted derivatives. The luminescent layer may have a thickness, for example, in a range of 400 to 1000 nm.
On the luminescent layer, there is a second dielectric layer 27 which may be substantially similar to the first dielectric layer, comprising nanolaminate with alternating AI2O3 and HfO2 sub-layers 28, 29.
The first dielectric layer 23 has as its uppermost sublayer, adjacent to the luminescent layer 26, an additional sub-layer 24' of aluminum oxide AI2O3. Correspondingly, the second dielectric layer 27 has as its lowermost sub-layer, adjacent to the luminescent layer 26, an additional sub-layer 28' of aluminum oxide AI2O3. Those aluminum oxide sub-layers have thicknesses higher than the aluminum oxide sub-layers of the actual nanolaminates. The thicknesses of the additional sublayers may lie, for example, in the range of 5 to 25 nm.
On the second dielectric layer 27, i.e. on top of the structure illustrated in FIG. 2, there is a second conductive electrode layer 30 which may be substantially similar to the first conductive electrode layer 22, with the stripes 31 thereof however being directed
perpendicularly to , or otherwise at an angle relative to , the conductor stripes of the first dielectric layer 22 .
The EL display element may be transparent . Then, also the first and the second electrode layers may be formed of a transparent conductor material such as , for example , indium tin oxide ITO . In the case of depositing also the electrode layers by ALD, suitable materials include , for example , aluminum doped zinc oxide AZO .
The display element 20 of FIG . 2 thus has a matrix electrode configuration . In other embodiments , segmented electrode configurations may be used .
In the matrix electrode configuration, light-emitting areas in the form of pixels 32 are formed in the luminescent layer 26 at positions where the conductor stripes of the first and the second conductive electrode layers intersect .
Any appropriate further layers and/or elements may be present in an EL display element in addition to those illustrated in FIG . 2 .
In any embodiment of the method and the EL display element discussed above , hafnium content of the first and/or the second dielectric layer is preferably at least 10 % by mass . This refers to the mass of the hafnium contained in a dielectric layer being at least 10 % of the overall mass of that layer .
In first and/or second dielectric layer where the hafnium content is at least 10 % by mass , aluminum content is preferably at least 5% by mas s . This refers to the mass of the aluminum contained in such dielectric
layer being at least 5% of the overall mass of that layer .
The EL display element of FIG . 2 may provide various great advantages . First , as discussed above with reference to FIG . 1 , the thin glass substrate serves for achieving a low overall thickness of the EL display component . This , in turn, enables having the overall EL display element as a flexible structure which may be further laminated or otherwise attached to a flexible and/or curved external substrate .
In addition , the EL display element in accordance with that of FIG . 2 has been found to have excellent stability performance . Enhanced stability results in reduced need for aging the displays in the manufacturing phase . Further, the stability of the voltage-luminance dependency may be greatly advantageous from the display element driving scheme points of view .
It wi ll be understood that the benef its and advantages described above may relate to one embodiment or example or may relate to several embodiments or examples . The embodiments and examples are not limited to those that solve any or all of the stated problems or those that have any or al l of the stated benefits and advantages . It will further be understood that reference to ' an ' item refers to one or more of those items .
The term "compris ing" i s used in thi s specification to mean including the feature ( s ) or act ( s ) followed thereafter, without excluding the presence of one or more additional features or operations .
Claims
1. An inorganic thin film electroluminescent display element (20) having a layer structure comprising:
- a first dielectric layer (23) , a luminescent layer (26) , comprising a luminescent material, on the first dielectric layer, and a second dielectric layer (27) on the luminescent layer, c h a r a c t e r i z e d in that each of the first and the second dielectric layers (23, 27) comprises nanolaminate with alternating aluminum oxide AI2O3 and hafnium oxide HfCy sub-layers (24, 25, 28, 29) , the nanolaminate having at least two sub-layers of both types .
2. An electroluminescent display element (20) as defined in claim 1, wherein the nanolaminate has a thickness of less than or equal to 300 nm.
3. An electroluminescent display element (20) as defined in claim 1 or 2, wherein a HfCy sub-layer (25, 29) has a thickness in the range of 1 to 10 nm, for example, 1 to 3 nm, for example, about 2 nm.
4. An electroluminescent display element (20) as defined in any of claims 1 to 3, wherein the nanolaminate of at least one of the dielectric layers comprises at least ten HfCy sub-layers (25, 29) each having a thickness in the range of 0.5 to 3 nm.
5. An inorganic thin film electroluminescent display element (20) as defined in any of claims 1 to 4, wherein an AI2O3 sub-layer (24, 28) has a thickness in the range of 1 to 10 nm, for example, 3 to 9 nm, for example, about 6 nm.
6. An inorganic thin film electroluminescent display element (20) as defined in any of claims 1 to 5, wherein hafnium content of the first and/or the second dielectric layer (23, 27) is at least 10% by mass.
7. An inorganic thin film electroluminescent display element (20) as defined in claim 6, wherein, in first and/or second dielectric layer (23, 27) where the hafnium content is at least 10%, aluminum content is at least 5% by mass.
8. An inorganic thin film electroluminescent display element (20) as defined in any of claims 1 to 7, wherein the luminescent material is manganese-doped zinc sulfide ZnS:Mn or terbium-doped zinc sulfide ZnS:Tb.
9. An inorganic thin film electroluminescent display element (20) as defined in any of claims 1 to 8, wherein the layer structure is formed on a glass substrate (21) having a thickness of less than or equal to 400 pm, preferably less than or equal to 100 pm.
10. An inorganic thin film electroluminescent display element (20) as defined in any of claims 1 to 9, wherein the display element is transparent.
11. A method for manufacturing an inorganic thin film electroluminescent display element, the method comprising forming a layer structure as defined in any of claims 1 to 10.
12. A method as defined in claim 11, wherein the first and the second dielectric layers are formed by atomic layer deposition.
13. A method as defined in claim 12, wherein the hafnium oxide sub-layers are formed using
19 tris (dimethylamino ) cyclopentadienylhaf nium CpHf (NMe2 ) 3 as a precursor for hafnium .
14 . A method as defined in any of claims 11 to 13 , wherein the luminescent layer is formed by atomic layer deposition using a maximum process temperature in the range of 125 to 300 °C, preferably 175 to 250 °C, most preferably 200 to 225 °C, for example 210 °C .
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI20215883 | 2021-08-24 | ||
FI20215883 | 2021-08-24 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2023025986A1 true WO2023025986A1 (en) | 2023-03-02 |
Family
ID=83283500
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FI2022/050542 WO2023025986A1 (en) | 2021-08-24 | 2022-08-23 | Inorganic tfel display element and manufacturing method |
Country Status (1)
Country | Link |
---|---|
WO (1) | WO2023025986A1 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6113977A (en) | 1996-09-11 | 2000-09-05 | Planar International Oy Ltd. | Method of growing a ZnS:Mn phosphor layer for use in thin-film electroluminescent components |
WO2018042079A1 (en) * | 2016-09-02 | 2018-03-08 | Beneq Oy | Inorganic tfel display element and manufacturing |
-
2022
- 2022-08-23 WO PCT/FI2022/050542 patent/WO2023025986A1/en unknown
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6113977A (en) | 1996-09-11 | 2000-09-05 | Planar International Oy Ltd. | Method of growing a ZnS:Mn phosphor layer for use in thin-film electroluminescent components |
WO2018042079A1 (en) * | 2016-09-02 | 2018-03-08 | Beneq Oy | Inorganic tfel display element and manufacturing |
Non-Patent Citations (3)
Title |
---|
KRASNOV A N ED - RADAMSON HENRY ET AL: "Selection of dielectrics for alternating-current thin-film electroluminescent device", THIN SOLID FILMS, ELSEVIER, AMSTERDAM, NL, vol. 347, no. 1-2, 22 June 1999 (1999-06-22), pages 1 - 13, XP004363571, ISSN: 0040-6090, DOI: 10.1016/S0040-6090(98)01763-5 * |
TSAKONAS COSTAS ET AL: "Transparent and Flexible Thin Film Electroluminescent Devices Using HiTUS Deposition and Laser Processing Fabrication", IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY, IEEE, USA, vol. 4, no. 1, 2 November 2015 (2015-11-02), pages 22 - 29, XP011594830, DOI: 10.1109/JEDS.2015.2497086 * |
YOSHIMASA A. ONO: "Electroluminescent Displays", 1995, WORLD SCIENTIFIC PUBLISHING CO. |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP3508035B1 (en) | Inorganic tfel display element and manufacturing | |
JP5093694B2 (en) | Oxide perovskite thin film EL device | |
KR100606642B1 (en) | Target for transparent conductive thin film, Transparent conductive thin film and Manufacturing method thereof, Electrode material for display, and Organic electroluminescence element and solar Cell | |
EP2061041A1 (en) | Conductive film and method for production of conductive film | |
TWI236861B (en) | Electroluminescence panel | |
KR19980048999A (en) | Transparent conductive laminate and EL light emitting device using same | |
CN108231849A (en) | display device, device and display control method | |
EP2704226A2 (en) | Substrate for oled and method of manufacturing the same | |
CN105161585A (en) | Fibrous quantum dot light emitting diode and manufacturing method thereof | |
Jiang et al. | AgNWs/AZO composite electrode for transparent inverted ZnCdSeS/ZnS quantum dot light-emitting diodes | |
JP4269986B2 (en) | Oxide sintered compact target for manufacturing transparent conductive thin film, transparent conductive thin film, transparent conductive substrate, display device, and organic electroluminescence element | |
WO2023025986A1 (en) | Inorganic tfel display element and manufacturing method | |
US6025677A (en) | Blue light emitting thiogallate phosphor including a thin nucleation layer of strontium sulfide | |
CN114026703A (en) | Quantum dot light-emitting structure, manufacturing method thereof, array substrate and display device | |
CN1527648A (en) | Organic electroluminesence device | |
JPS62145694A (en) | Electric field light emitting device and manufacture of the same | |
CN108565361B (en) | OLED capsule structure, OLED light-emitting layer, related method, display panel and electronic equipment | |
JP2009301885A (en) | Multi-unit type organic el element, and method for manufacturing the same | |
CN1549659A (en) | Apparatus and method for raising chroma of high-polymer organic light-emitting diode elements | |
KR100373320B1 (en) | method for fabricting AC driving type electroluminescent devices using Ta2O5 layer | |
EP1554913A1 (en) | Thin film phosphor for electroluminescent displays | |
JPS6391995A (en) | Thin film el device | |
US20110241046A1 (en) | Light Emitting Device Having Peripheral Emissive Region | |
WO2023084154A1 (en) | Thin film electroluminescent display element and manufacturing | |
JP4033238B2 (en) | Ballistic electron field emission electron source and manufacturing method thereof |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 22769312 Country of ref document: EP Kind code of ref document: A1 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |